The present disclosure relates generally to toner and developer compositions, useful in electrostatographic, electrophotographic, xerographic, and the like machines, including printers, copiers, scanners, facsimiles, and the like, and including digital and image-on-image machines. More specifically, the disclosure relates to toner compositions comprising-dual wax combination. In embodiments, the dual wax combination comprises a polyethylene wax in combination with a Carnauba wax.
Methods of preparing emulsion aggregation (EA) type toner are known. Toners may be formed by aggregating a colorant with a latex polymer formed by batch or semi-continuous emulsion polymerization. For example, U.S. Pat. No. 5,853,943, the disclosure of which is hereby incorporated by reference in its entirety, discloses a semi-continuous emulsion polymerization process for preparing a latex by first forming a seed polymer. In particular, the '943 patent describes a process comprising: (a) conducting a pre-reaction monomer emulsification comprising emulsification of the polymerization reagents of monomers, chain transfer agent, a disulfonate surfactant or surfactants, and optionally, an initiator, wherein the emulsification is accomplished at a low temperature of, for example, from about 5° C. to about 40° C.; (b) preparing a seed particle latex by aqueous emulsion polymerization of a mixture comprising (i) part of the monomer emulsion, for example, from about 0.5 to about 50 percent by weight, or from about 3 to about 25 percent by weight, of the monomer emulsion prepared in (a), and (ii) a free radical initiator, from about 0.5 to about 100 percent by weight, or from about 3 to about 100 percent by weight, of the total initiator used to prepare the latex polymer at a temperature of from about 35° C. to about 125° C., wherein the reaction of the free radical initiator and monomer produces the seed latex comprising latex resin wherein the particles are stabilized by surfactants; (c) heating and feed adding to the formed seed particles the remaining monomer emulsion, from about 50 to about 99.5 percent by weight, or from about 75 to about 97 percent by weight, of the monomer emulsion prepared in (b), and optionally a free radical initiator, from about 0 to about 99.5 percent by weight, or from about 0 to about 97 percent by weight, of the total initiator used to prepare the latex polymer at a temperature from about 35° C. to about 125° C.; and (d) retaining the above contents in the reactor at a temperature of from about 35° C. to about 125° C. for an effective time period to form the latex polymer, for example from about 0.5 to about 8 hours, or from about 1.5 to about 6 hours, followed by cooling. Other examples of emulsion/aggregation/coalescing processes for the preparation of toners are illustrated in U.S. Pat. Nos. 5,290,654, 5,278,020, 5,308,734, 5,370,963, 5,344,738, 5,403,693, 5,418,108, 5,364,729, and 5,346,797, the disclosures of each of which are hereby incorporated by reference in their entirety. Other processes are disclosed in U.S. Pat. Nos. 5,348,832, 5,405,728, 5,366,841, 5,496,676, 5,527,658, 5,585,215, 5,650,255, 5,650,256 and 5,501,935, the disclosures of each of which are hereby incorporated by reference in their entirety.
Currently, some known EA toner formulations use a single wax (for example, polyolefin, such as polyethylene or polypropylene). The present disclosure describes the replacement of the use of a single polyolefin with a combination of synthetic and a second, different wax. The use of the combination of different waxes is believed to increase the release function of the EA toner. The result is ease of cleaning of the photoreceptor. In addition, polyolefin waxes are expensive. Therefore, by cutting back on the amount of wax by using a combination of two different waxes, an EA toner can be produced at a lower cost.
Toner builds up on the thermister, striper fingers and the cleaning web. This toner deposits itself on the back of copies. The dual wax formulation allows greater release properties and a more uniform distribution of surface additives and consequently a more uniform charge distribution on the surface of the toner. This eliminates or minimizes toner deposits on the stripper fingers, thermister, and cleaning web.
Therefore, it is desirable to provide a toner which solves or reduces fusing defects. It is further desired to provide an EA toner that can be prepared with less wax, in order to decrease the cost of production of the EA toner. The lower amount of total wax yields less wax on the toner surface. This allows lower amounts of external toner additives to be used and lowers the cost. Less wax on the surface also facilitates increased toner flow and a more uniformed surface charge. The lower melting wax would allow faster copier speeds and/or lower fusing temperatures.